- This patch adds in support to accept the "#" character as part of an Identifier.
- This support is needed especially for the HLASM dialect since "#" is treated as part of the valid "Alphabet" range
- The way this is done is by making use of the previous precedent set by the AllowAtInIdentifier field in MCAsmLexer.h. A new field called AllowHashInIdentifier is introduced.
- The static function IsIdentifierChar is also updated to accept the # character if the AllowHashInIdentifier field is set to true.
Note: The field introduced in MCAsmLexer.h could very well be moved to MCAsmInfo.h. I'm not opposed to it. I decided to put it in MCAsmLexer since there seems to be some sort of precedent already with AllowAtInIdentifier.